Neck straightening device for musical instruments



Oct. .6, 1936. A. B. 1 ow 2,056,474

NECK STRAIGHTENING DEVICE FOR MUSICAL INSTRUMENTS Filed Feb. 15, 1935 F7 I 4k u E 22/ INVENTOR. d5

4/ THUR 5 O Patented Oct. 6, 1936 UNITED STATES PATENT OFFICE NECK STRAIGHTENING DEVICE FOR MUSICAL INSTRUMENTS This invention relates to improvements in necks for musical instruments, such as banjos and guitars.

It has been found that in musical instruments 5 of the stringed type, provided with long wooden necks, the necks are liable to warp or bow due to the constant severe strains to which they are subjected from the strings. This occurs most frequently in moist climates, or when the instrument is transferred from a dry to a moist climate or vice versa.

When the necks get bowed it interferes in some degree with the playing of the instrument and is therefore objectionable.

It is the object of this invention to produce a simple and effective means for returning instru ment necks to normal position after they have become bent or twisted by the action of the strains to which they are subjected and/or to climatic conditions.

Another object of this invention is to produce a device for straightening the necks of musical instruments that can be applied either at the factory or after the instrument has been in use 25 for some time.

The above and other objects that may become apparent as the description proceeds are attained by means of a construction and an arrangement of parts that will now be described in detail and 3 for this purpose reference will be had to the accompanying drawing in which the invention has been illustrated in its preferred form and in which Fig. 1 is a longitudinal section of a banjo con- 35 structed in accordance with the invention;

Fig. 2 is a longitudinal section through a banjo neck showing the straightening device removed therefrom;

Fig. 3 is a side elevation of the straightening 40 device;

Fig. 4 is a side elevation, partly in section, showing a worm gear drive for turning the straightening device;

Fig. 5 is a section taken on line 5-5, Fig. 4;

Fig. 6 is a fragmentary longitudinal section showing a slightly modified construction;

Fig. '7 is an end elevation of the device shown in Fig. 6;

Fig. 8 is a cross section taken on line 88,

Fig. 6;

Fig. 9 is a longitudinal section showing a modification;

Fig. 10 is a cross section taken on line 10-10,

55 Fig. 9;

Fig. 11 is an end view of the device shown in Fig. 9-;

Fig. 12 is a longitudinal section showing a still further modification;

Fig. 13 is an end elevation of the device shown in Fig. 12;

Fig. 14 is a longitudinal section showing a further modification;

Fig. 15 is a section taken on line l5-l5, Fig. 14; and

Fig. 16 is a fragmentary section showing a bevel gear drive.

In the drawing numeral 5 designates the instrument neck in all of the views. The end designated by numeral 6 contains the pegs for ten- 15 sioning the strings while the end 1 is enlarged and attached to the resonating body 8 by any suitable means. The necks are usually provided with a brace bar 9.

Due to strains and climatic conditions, necks 20 of stringed musical instruments frequently become bowed as shown in Fig. 2, where the top has been shown as concave; when this occurs the instrument becomes difficult to play.

An instrument neck made in accordance with this invention is provided with a hole l0 extending longitudinally therethrough and this hole is originally straight. A rod H of steel or any other resilient material such as spring brass is longitudinally bowed, as shown in Fig. 3, and is provided with a handle portion l2 that serves as a crank arm for turning the rod after it has been inserted into the hole. Rod H is inserted into the hole H], as shown in Fig. 1, and since the hole is straight, the rod will straighten as it is inserted.

The bending strains set up by the action of the bowed rod in the straight hole produces a fiexure of the neck which bows it in conformity to the bow-of the rod and the extent of this flexure depends on the relative rigidity of the neck and the rod. In the drawing the plane of the curvature of the rod has been shown as lying in the axis of the handle I2.

It is obvious that by turning the rod in the hole the plane of the fiexure will be rotated. When the rod, shown in Fig. 3, is inserted into the hole in the bowed neck shown in Fig. 2, the rod will produce a bending force that will remove the curvature from the neck when it is properly adjusted. It is evident that if the rod is so positioned that its plane of curvature lies parallel with the top surface of the neck it will tend to bend the neck sidewise and this is eifectively resisted by the composition top I4 with which 5 such necks are provided and any small sidewise curvature that may be produced has been found to be unobjectionable. By turning the rod so that the convex side will be on'topit tends to bow the neck upwardly a maximum amount and this component is controlled by angle that the plane of the curvature makes with the top of the neck.

In Figs. 6, '7, and 8a modificationhas been shown in which the hole ma is oblong and two rods are'employed; by rotating these rods equally and in opposite directions all sidewise bendin forces are neutralized.

In Figs. 4 and. 5 a worm gear mechanism has been illustrated for turning the rod in place of the handle 12. The rod is provided with a worm wheel l5 and a worm I6 is rotatably' mounted in a, threaded bearing block ll inqthe mannerishown in Fig. 5. The wormshaft I8 is provided with of. these holes.

a screw driver slot l9. In Fig. 16 a bevelgear' mechanism has been shown for turning rod II, and the end of the rod has a bevel gear 20 applied thereto and this cooperateswith a similar gear 2! carried by shaft 22 which is mounted for rotation in'tube 23 and provided with a screw driver slot 24. r V It sometimes happens that the necks warp or twist as well as bend and althoughthisis a less frequent occurrence, it is objectionable when it occurs and in Figs. 9 to 15, means have been illustrated for correcting a twist as well asalongitudinal bendQ 7 In Figs. 9; and a tube 25 has been shown as located in the hole It] and its end secured against rotation by a pin 26. A washer if! is slidably secured to the rear end of the tube and this is provided with a number of holes 28 arranged in a circle. A pin 29 is secured to the endof the neck and so positioned that it can enter any one 7 e By twisting the tube until a sufficient torsional strain is produced to remove the twist in the neck and then sliding the washer forwardly until the pin entersone of the holes therein the twistwill be removed. The rod II is inserted into the tube. In the drawing, tube Zdhas been shown as hexagonal but this is not essential. V V r In Figs. 12 and 13, a reversal of the construc tion illustrated in Figs. 9, 10, and 11 has been shown. In this construction the rod Ila is straight and has its inner end held against turningby a pin 30, which projects through a hole in the end of the rod and through the neck in the same manner as pin 26 holds the tube 25 in Figure 9. 'By twisting the rod the necessary torsional strains for removing the twist from the neck can be produced. A pin 3| holds the rod Illa from untwisting, and can be positioned in any one'of the holes 32. The tube 25a is bowed and takes the placed of the bowed rod ll and has its outer end provided with a hexagonal portion 33 by means of which it can be turned to effect the necessary straightening action.

'In Figs. 14; and 15, a modification has been shown in which the rod H can be employed for removingv a warp or twist as well as. a bend from the neck. The rod is'provided withthe worm gear means for turning it, which has been shown in Figs. 4 and 5. The inner end of'the rod pro- 'jects through a metal block 34 and can be clamped against rotation in this'block' by a's'et screw 35.

' If a twist alone is to' be removed, the inner end ofj the rod'is clampedagainst rotation after which; the worm device is operated to twist the essential to this invention, in its broadest aspect, that the resilient member H, which is usually of metal. but may .b'e.made of any suitable resilient :material; shall be rotatable in the hole or opening, as it is possible to straighten the neck by drilling a hole and inserting a bowed resilient 'member ofsuch strength and curvature that it v will produce the required straightening force and insert this'i'member in the opening so as to produce the necessary straightening eifect. Instead ofa .Solid rod, a tube can be "used, as this has greater strength per unit weight than a solid member.

Having described the invention, what is claimed asnewisz- 1. A stringed musical instrument neck having a substantially straight, hole extending longitue dinally therethrough, atube located in the hole, means for securing one end of the tube. against rotation relative to the neck, and means at, the other end of the tube for rotating it relative, to the neck whereby torsional strains are produced which tend to twist the neck. 7 v l w 2. A stringed musical instrument neck having a substantially straight hole extending longitudinally therethrough, a tube located in the hole, means for securing one end of the tube against rotation relative to the neck, means at the other end of the tube for rotating it relative to the neck whereby torsional strains are produced which tend to twist the neek, a normally curved resilient metal rod located in the tube, and means for rotating the rod. V

3. A stringed musical instrument neck provided with a substantially straight hole extending longitudinally therethrough, an elongated normally curved member of resilient material located'in the opening for subjecting the neck to a flexing strain, and means for rotating the member in the hole whereby the plane of the flexing forces will be rotated about the center of the hole. V

4. A stringed musical instrument neck pro vided with a substantially straight hole extending longitudinally'therethrough, an elongated, normally, curved member of resilient material located in the opening for subjecting the neck to a flexing strain, and means comprising a' worm gear drive for rotating the member in. the hole whereby the plane ofthe flexing forces will be rotated about the center of the hole.

5. A stringed musical instrument neck 'pro in the opening for subjecting the neck to a flexing strain, and means comprising a crank arm for rotating the member in the hole whereby the plane of the flexing forces will be rotated about the center of the hole.

7. A stringed musical instrument neck provided with a substantially straight hole extending longitudinally therethrough, an elongated, normally curved member of resilient material located in the opening for subjecting the neck to a flexing strain, means for rotating the member in the hole, and means located in the hole, in concentric relation to the curved member for applying torsional forces to the neck.

8. A neck for a stringed musical instrument having a hole extending in the direction of its length and a resilient member located in the hole, said member before it is inserted into the hole being curved relative to the longitudinal axis of the hole.

9. A stringed musical instrument neck provided with a straight hole extending longitudinally therethru, and a normally longitudinally curved member of resilient material located in the hole whereby the neck will be subjected to a bending action.

10. A stringed musical instrument neck proa substantially straight hole extending longitudinally therethru, means for applying a torsional strain to the neck, comprising an elongated mem-- ber of resilient material located in the hole, means at one end of the member for holding it from rotating relative to the neck, means at the other end of the member for rotating it relative to the neck to adjust the torsional strain, means for interconnecting the neck and torsion member,

to retain the torsional strain, means for apply ing a force to the neck for bending it, comprising a normally curved, elongated resilient member also located in the hole in the neck, and manually operable means connected with one end of said bending member to rotate it relative to the neck.

ARTHUR B. LOW. 

